Light-valve transmitter



Dec. 117, 1929. c. F. JENKINS L'MQBEZ LIGHT VALVE TRANSMITTER Fild June25, 1927 Patented Dec. 17, 1929 UNITED sates PATENT OFFICE CHARLESFRANCIS JENKINS, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TOJENKINS LABORATORIES, OF WASHINGTON, DISTRICT OF COLUMBIA, A. COR-PORATION OF THE DISTRICT OF COLUMBIA LIGHT-VALVE TRANSMITTER Applicationfiled June 25,

v m suiting pulsating current output can be amplified in transformercoupled units, the

amplifier preferred by radio engineers.

However, as the oscillating frequencies possible with a mechanicallight-chopper are very limited, and can not at all approach the 250,000per second oscillating frequency required in radio vision and radiomovies, it

has been found desirable to use a gas-cell light-valve of the type shownin my co-pending application Serial No. 200,752, filed June lViththis'and other objects in view the invention consists in the novelcombination of parts hereinafter described, and more particularlypointed out in the claims.

Fig. 1 shows one preferred manner of utilizing the invention.

Fig. 2 shows a detail of the light valve of Fig. 1.

In the drawing, accompanying this specification, A is a source of light;B a condensing lens; G a motion picture film; D a.

sprocket for continuously advancing the film across the light; E arotating lens-disc for imaging the successive frames on the picturefilm, and sweeping them across the gaseous light-valve F, located infront of the aperture in the cell enclosing box G. This apparatus isdisclosed and claimed in United States Patent 1,559,137. H is thelight-cell.

The light-valve F consists of a tubular cathode F insulated by a glasssleeve from the. enclosing anode. When alternating current circuits ofsuitable high frequency are connected to this cathode-anode cell, the

cathods fills with a gaseous glow which blocks the entrance to thelight--cell on every positive phase, and permits thelightto pass on theopposite phase.

This action of the light-valve produces a and a gaseous light-valvelocated to periodi- 1927. Serial No. 201,400.

pulsating current in the output circuit of the cell, which can beamplified in transformer amplifiers.

As this type of light-valve has a frequency limit approaching infinity,it is obviously suitable for the purpose here shown.

Of course, I do not wish to limit myself to this particular valve, asany fluid light-valve which permits the whole light to pass at the.required hi h frequencies would answer.

What I c aim, is-

1. In combination, picture-image producing means, a light-sensitive cellupon which the light of said picture-image may fall, and a gaseousdischarge light-valve located between said image producing means andsaid light-sensitive cell and operable at radio frequencies with minutecurrents generally available in radio work.

2. In combination, a modulated light beam, a light-sensitive cell and agaseous lightvalve located in the path of said beam to periodicallypermit light access to said cell and operable at radio frequencies withminute currents generally available in radio work.

3. In combination, a motion-picture film, means for scanning successiveframes of said film, -a light-sensitive cell upon which the image ofsaid picture frames may impinge,

cally intercept the light from said film impinging on. said light-celland operable at radio frequencies with minute currents generallyavailable in radio work.

1. The method of'transmitting an image electrically which comprisescollecting the light from successive elemental areas of the image,passing said light through a gaseous discharge light valve, andproducing photoelectric currents under control of the light after itpasses said valve.

The method according to claim 4, in which the light valve iscontinuously operated by high frequency currents.

G. The method of transmitting an image electrically at radio frequencieswhich comprises collecting the light from successive elemental areas ofthe image, passing said light through a gaseous dischargevalve, varyingthe intensity of the said discharge in accord- 100 ance with the highfrequency current and producing photo-electric currents corresponding tothe light which passes said valve.

7. In a system for electrically transmitting 5 images, the method ofproducing a carrier current and simultaneously modulating same by alight beam which comprises continually operating a gaseous dischargelight valve by alternating current, passing a modulated .10 light beamthrough said valve, and projecting said. modulated beam after passingthrough said' valve, upon a photo-sensitive device. 4

8. In an image transmission system the 15 combination of means foranalyzing succes sive elemental areas of .the image to produce acorrespondingly modulated light beam, a substantially inertialess aseousdischarge valve, means for continua 1y operating said 20 valve byalternating current, saidvalve being positioned in the path-of said'beamand a photo-sensitive device energized by said beam after passingthrough said valve.

9. A system according to the preceding 25 claim in which the light valveis of the rectifying ype In testimony whereof I have affixed mysignature.

CHARLES FRANCIS JENKINS. so I

